Do just one

1. Use substrings to implement a version of the GPA calculator which handles course credits (so you need to compute a weighted average of grades) and allows for '+' and '-' grades to be entered. You should process grades the way Oneonta does, where A+  and E- are not legal.
2. Complete the third lab for this week. (See lab links). Then extend its functionality by computing (and displaying) the sum, average and standard deviation of the values in the data file. There are several formulas used for standard deviation and variance. One set of formulas is:

Mean = 1/n(S x_i)

Variance = 1/(n-1)S( x_i-mean)²

SD= sqrt(variance)

If n is the count of data values, another formula for variance is 1/(n-1)[Sx_i²-n*mean²]

This second formula does not require reading through the data twice.

3. Complete the basechanger lab. Then build a base changer for converting from base 10 to another base, or converting from another base to base 10. Handle exceptions and bases up to 16.